1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for performing a prescribed processing to a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask, and a substrate for an optical disc and inspecting the substrate.
2. Description of the Background Art
Products such as a semiconductor device and a liquid crystal display are produced by subjecting a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask, and a substrate for an optical disc to a series of processings. The processings include cleaning, resist-coating, exposure, development, etching, forming an interlayer insulating film, heat-treatment and dicing. In order to maintain the qualities of the semiconductor products or the like, the substrates must be inspected for various aspects to verify the qualities.
For controlling a resist coater in particular, the resist film thickness is controlled for the purpose of keeping the line width (Critical Dimension) from fluctuating. The resist film thickness is controlled by inspection using a thicknessmeter provided in the resist coater, or sampling inspection. When a value measured using the thicknessmeter is outside the range of a prescribed target control value, for example, the number of revolutions of the spin coater that applies resist while rotating the substrate is changed in order to control the thickness.
Meanwhile, the demand for higher line width uniformity has grown with recent reduction in the processing dimension. At present, a KrF (krypton fluoride) excimer laser (wavelength: 248 nm) is mainly used as a light source for exposure in producing on a substrate a pattern whose line width is in the range from 0.18 to 0.13 μm. There is a prospect for the use of an ArF (argon fluoride) excimer laser (wavelength: 196 nm) for a line width in the range from 0.13 to 0.1 μm or an F2 (fluorine dimer) excimer laser (wavelength: 157 nm) for a line width in the range from 0.1 to 0.07 μm. More improvement in the line width precision is called for as well.
If however the film thickness is controlled to be uniform by the conventional inspection by the film thickness measurement, difference in the process caused by different coating conditions or heat-treatment conditions makes it difficult to keep the line width uniform after development.